This invention relates to heat exchangers using sparged liquid refrigerant in cryogenic plants.
It is known to utilize a heat exchanger employing a sparged liquid into a cold vapor, the resulting mixture being passed in heat exchange relationship with a hotter vapor as shown by Young U.S. Pat. No. 3,895,676 issued July 22, 1975, the disclosure of which is hereby incorporated by reference. Such heat exchangers are particularly useful in liquefying gases as, for instance, in the production of liquefied natural gas. In such operations there is a problem of maintaining good heat transfer during variations in the loading (throughput). As a result of various factors such as partial shutdown for repairs and maintenance, changes in the production rate of the natural gas, and the like, the heat load on the heat exchangers in terms of the volume of hot vapor may vary by as much as a factor of 10. In an ordinary heat exchanger, such variation may be tolerated. However, in heat exchangers employing as a refrigerant a cold liquid sparged into a cold vapor, a decreased heat load reduces the volume of refrigerant which causes a maldistribution of the liquid phase into the parallel heat exchange passageways and ultimately insufficient vaporization of the cold liquid and flooding and blockage of some of the refrigerant passageways and no liquid in others. This causes a severe loss of efficiency in the heat exchange operation with recognition and positive action being required to correct such a condition.